US Republican presidential hopeful Rick Santorum has won the Kansas caucuses with 53 per cent of the vote, giving him a boost going into crucial primary votes in the South next week.

With 83 per cent of votes counted, the Christian conservative, former senator from Pennsylvania was well ahead of former Massachusetts governor Mitt Romney with 17 per cent, and former House of Representative Speaker Newt Gingrich with 15 per cent, CNN said on Saturday.

Texas congressman Ron Paul had 13 per cent.

"I congratulate Rick Santorum on winning the Kansas caucus. I also thank all of our candidates for their dedication to ending Barack Obama's failed presidency," Republican national committee chairman Reince Priebus said in a statement.

"Today, Kansans made their voices heard and voted for a new direction," the statement said. "They know America cannot afford four more years of Barack Obama."

The win gives Santorum bragging rights ahead of the more contested races next week in Alabama and Mississippi, where with further victories he could solidify his status as the conservative alternative to front-runner Romney.

Winning Kansas' value "is in not dropping the ball," said Ruy Teixeira, political analyst at the liberal Center for American Progress.

Santorum visited the flat plains and rolling hills of Kansas more than any other candidate, appearing at rallies on Wednesday and Friday.